In 1997, he married Jean Fetter, a British-American Oxford-trained physicist.[24] He has two sons, Geoffrey and Michael, from a previous marriage to Lisa Chu-Thielbar.[10]

Chu is interested in sports such as baseball, swimming, and cycling. He taught himself tennis—by reading a book—in the eighth grade, and was a second-string substitute for the school team for three years. He also taught himself how to pole vault using bamboo poles obtained from the local carpet store.[10] Chu said he never learned to speak Chinese because his parents always spoke to their children in English.[24]

After obtaining his doctorate he remained at Berkeley as a postdoctoral researcher for two years before joining Bell Labs, where he and his several co-workers carried out his Nobel Prize-winning laser cooling work. He left Bell Labs and became a professor of physics at Stanford University in 1987,[10] serving as the chair of its Physics Department from 1990 to 1993 and from 1999 to 2001. At Stanford, Chu and three others initiated the Bio-X program, which focuses on interdisciplinary research in biology and medicine,[29] and played a key role in securing the funding for the Kavli Institute for Particle Astrophysics and Cosmology.[30] In August 2004, Chu was appointed as the director of the Lawrence Berkeley National Laboratory, a U.S. Department of Energy National Laboratory, and joined UC Berkeley's Department of Physics and Department of Molecular and Cell Biology.[31] Under Chu's leadership, the Lawrence Berkeley National Laboratory has been a center of research into biofuels and solar energy.[20] He spearheaded the laboratory's Helios project, an initiative to develop methods of harnessing solar power as a source of renewable energy for transportation.[31]

Chu's early research focused on atomic physics by developing laser cooling techniques and the magneto-optical trapping of atoms using lasers. He and his co-workers at Bell Labs developed a way to cool atoms by employing six laser beams opposed in pairs and arranged in three directions at right angles to each other. Trapping atoms with this method allows scientists to study individual atoms with great accuracy. Additionally, the technique can be used to construct an atomic clock with great precision.[32]

Chu received an honorary doctorate from Boston University when he was the keynote speaker at the 2007 commencement exercises.[35] He is a Senior Fellow of the Design Futures Council.[36]Diablo Magazine awarded him an Eco Awards in its April 2009 issue,[37] shortly after he was nominated for Energy Secretary.

Steven Chu’s development of methods to laser cool and trap atoms was recognised by the award of the Nobel Prize in Physics in 1997. He also pioneered the development of atom interferometry for precision measurement, and he introduced methods to visualize and manipulate single bio-molecules simultaneously with optical tweezers. Throughout his career, he has sought new solutions to the energy and climate challenges. From January 2009 to April 2013, he was the 12th U.S. Secretary of Energy under President Barack Obama, and initiated the Advanced Research Projects Agency - Energy, the Energy Innovation Hubs, and the Clean Energy Ministerial meetings.[45]

In August 2011 Chu praised an advisory panel report on curbing the environmental risks of natural-gas development. Chu responded to the panel’s report on hydraulic fracturing, the controversial drilling method that is enabling a U.S. gas boom while bringing fears of groundwater contamination. The report called for better data collection of air and water data, as well as “rigorous” air pollution standards and mandatory disclosure of the chemicals used in the hydraulic fracturing process. Chu said that he would "be working closely with my colleagues in the Administration to review the recommendations and to chart a path for continued development of this vital energy resource in a safe manner".[53]

Chu faced controversy for a statement he made prior to being appointed, claiming in a September 2008 interview with the Wall Street Journal that "somehow we have to figure out how to boost the price of gasoline to the levels in Europe.”[54] However, in March 2012 he retracted this comment, saying "since I walked in the door as secretary of Energy I’ve been doing everything in my powers to do what we can to … reduce those prices” and that he "no longer shares the view [that we need to figure out how to boost gasoline prices in America]".[55]

On February 1, 2013, Chu announced his intent to resign.[57][17] In his resignation announcement, he warned of the risks of climate change from continued reliance on fossil fuels, and wrote, "the Stone Age did not end because we ran out of stones; we transitioned to better solutions".[58] He resigned on April 22, 2013.

Chu was instrumental in submitting a winning bid for the Energy Biosciences Institute, a BP-funded $500 million multidisciplinary collaboration between UC Berkeley, the Lawrence Berkeley Lab, and the University of Illinois. This sparked controversy on the Berkeley campus, where some fear the alliance could harm the school’s reputation for academic integrity.[63][64][65][66]

Based partially on his research at UC Berkeley, Chu has speculated that a global "glucose economy", a form of a low-carbon economy, could replace the current system. In the future, special varieties of high-glucose plants would be grown in the tropics, processed, and then the chemical would be shipped around like oil is today to other countries. The St. Petersburg Times has stated that Chu's concept "shows vision on the scale needed to deal with global warming".[23]

Chu has also advocated making the roofs of buildings and the tops of roads around the world white or other light colors, which may reflect sunlight back into space and mitigate global warming. The effect would be, according to Chu, similar to taking every car in the world off the roads for about 11 years.[23] Samuel Thernstrom, a resident fellow at the American Enterprise Institute and co-director of its Geoengineering Project, expressed support for the idea in The American, praising Chu for "do[ing] the nation a service" with the concept.[67]

^Müller, H.; Peters, A.; Chu, S. (2010). "A precision measurement of the gravitational redshift by the interference of matter waves". Nature. 463 (7283): 926–9. Bibcode:2010Natur.463..926M. doi:10.1038/nature08776. PMID20164925. According to Nature he worked on this "during nights, weekends and on planes – after putting in 70–80 hours a week as energy secretary"